linux-kernel - Re: [PATCH RESEND v2 0/3] condition EAS enablement on FI support

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Date:   Wed, 18 Nov 2020 11:42:34 +0000
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
        catalin.marinas@....com, will@...nel.org, rjw@...ysocki.net,
        viresh.kumar@...aro.org
Cc:     dietmar.eggemann@....com, qperret@...gle.com,
        valentin.schneider@....com, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v2 0/3] condition EAS enablement on FI support

Hi guys,

On Tuesday 27 Oct 2020 at 18:07:10 (+0000), Ionela Voinescu wrote:
> Given the maturity gained by cpufreq-based Frequency Invariance (FI)
> support following the patches at [1], this series conditions Energy
> Aware Scheduling (EAS) enablement on a frequency invariant system.
> 
> Currently, EAS can be enabled on a system without FI support, leading
> to incorrect (energy-wise) task placements. As no warning is emitted,
> it could take some debugging effort to track the behavior back to the
> lack of FI support; this series changes that by disabling EAS
> (and advertising it) when FI support is missing.
> 
> The series is structured as follows:
>  - 1/3 - create function that can rebuild the scheduling and EAS'
>    performance domains if EAS' initial conditions change
>  - 2/3 - arm64: rebuild scheduling and performance domains in the
>          case of late, counter-driven FI initialisation.
>  - 3/3 - condition EAS enablement on FI support
> 
> RESEND v2: rebase and retest on v5.10-rc1
> 

This still applies nicely on v5.10-rc4.

Peter, given that 1/3 and 2/3 are acked, do you think there's anything
else that needs to be done for this?

Thank you,
Ionela.

> v1 -> v2:
>  - v1 can be found at [2]
>  - 1/2 - moved now "static inline" rebuild_sched_domains_energy() stub
>    in sched/topology.h header, as suggested by Quentin.
>  - Changed the order of 2/3 and 3/3 to maintain bisection as suggested
>    by Quentin.
>  - 3/3 - place the warning under sched_debug() as per Quentin and
>    Dietmar's recommendations.
> 
> [1] Most recent version at:
> https://lore.kernel.org/lkml/20200901205549.30096-1-ionela.voinescu@arm.com/
> [2] https://lore.kernel.org/lkml/20200924123937.20938-1-ionela.voinescu@arm.com/
> 
> Many thanks,
> Ionela.
> 
> Ionela Voinescu (3):
>   sched/topology,schedutil: wrap sched domains rebuild
>   arm64: rebuild sched domains on invariance status changes
>   sched/topology: condition EAS enablement on FIE support
> 
>  arch/arm64/kernel/topology.c     | 10 ++++++++++
>  include/linux/sched/topology.h   |  8 ++++++++
>  kernel/sched/cpufreq_schedutil.c |  9 +--------
>  kernel/sched/topology.c          | 27 ++++++++++++++++++++-------
>  4 files changed, 39 insertions(+), 15 deletions(-)
> 
> 
> base-commit: 3650b228f83adda7e5ee532e2b90429c03f7b9ec
> -- 
> 2.17.1
>